Evidence for Sensory Memory

The classic studies on sensory memory were carried out by Sperling. Sperling used a chart containing three rows of letters, which he splayed for very brief exposures (50 milliseconds) to his participants.

Participants were immediately asked to recall as many of the letters as possible and could usually only recall about four or five. However, they frequently reported having been aware of more letters even though they couldn't recall them. Sperling decided to test this by changing his procedure slightly. He trained participants to distinguish between three tones. He then exposed the chart for the same amount of time but, this time, played one of the tones as soon as the chart had disappeared. Participants were instructed to recall the top row of letter in response to a high tone, the middle row in response to a medium tone and the bottom row in response to a low tone. Under these circumstances, participants were able to recall, on average, three items from whichever row had been cued by the tone. It is important to remember that participants did not know which row they would be asked to recall until after the display had disappeared. This suggests that, at that stage, they would have been able to recall an average of 3 letters…